Oyster is a kind of shellfish, and its shell can be divided into three layers in section. The outermost layer is a thin and transparent stratum corneum, the thickest layer is a columnar structure made of calcium carbonate called prismatic layer, and the inner layer is a flaky structure made of calcium carbonate called nacre.

Oysters, commonly known as oyster seeds and oysters, belong to mollusks. Bivalves, oysters and oysters are collectively called oysters. Oyster is the largest cultured shellfish in the world, one of the important marine biological resources available to human beings, and a globally distributed species.

There are many kinds of oysters, among which there are about 20 kinds of oysters with commercial value. The kinds of oysters that people can eat are usually from the genus Oyster and Oyster. They are not only delicious and nutritious, but also delicious seafood treasures.

morphological character

The shell is formed by the secretion of the lower mantle, which extends from the top of the shell to the edge of the abdomen. It is a membrane formed by two layers of epithelial cells, with connective tissue sandwiched between them, and muscle fibers in the membrane make it adhere to the inner surface of the shell. The edge of the mantle thickens to form three folds, and there are radial muscles and annular muscles on the inner folds to make the edge close to the shell. There are a large number of sensory cells or organs in the folds, which have tactile and visual functions.

The two shells are unequal, the left shell or the lower shell is large and concave, and the left shell is fixed on rocks or seabed stakes. Generally, in the later stage of metamorphosis, the foot silk secretes mucus, which fixes the edge of the mantle on the substrate, and then the shell secreted by the mantle directly adheres to the plug. The foot completely disappeared, the degeneration of the adductor muscle disappeared, and the adductor muscle moved to the middle of the body, completely losing its mobility.